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Measuring Diameter

A tree's diameter is measured by calipers, which consist of a graduated rule, marked in inches and fractions, a fixed arm forming a right angle at one end, and a movable arm, parallel with the first one, sliding on the rule. The rule is set against a tree above the bulge of the base. The fixed arm touches it at one point, and the sliding arm comes up to a point on the bark diametrically opposite. The base of this arm indicates the diameter of the tree on the scale of inches.

Logs and standing timber are measured by this tool. Calipers for ordinary work have rules four to five feet long. Few trees require longer ones.